Radial Variation in Distortion Transfer and Generation Through a Highly Loaded Fan Stage

Abstract

An important consideration for fan and compressor design is quantifying distortion transfer and generation blade row by blade row. Detailed information about the magnitude of distortion and the shape of the distortion profile and how it changes through blade rows increases the understanding of flow physics and helps predict aerodynamic performance. Using full annulus URANS simulations, this paper analyzes what happens to distortion as it passes through the rotor and stator blade rows at 10%, 30%, 50%, 70%, and 90% span. Fourier distortion descriptors are used in this study to quantitatively describe distortion transfer and generation. With these descriptors, evidence of pressure-induced swirl is shown at the fan inlet. It is also shown that although there is very little distortion at the 10% span of the inlet, after passing through the rotor blade row the 10% span has the greatest amount of total pressure and total temperature distortion. This radial migration of distortion is attributed to the high hade angle of the hub. The total pressure and total temperature profiles have significant circumferential phase shifts after passing through the rotor and slight phase shifts after passing through the stator. In general, the calculated phase shifts are greatest at the 10% and 90% spans, the nearest locations to the hub and the tip clearance gap, respectively.